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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 90 |
| 4 | 5040 |
| 5 | 529200 |
| 6 | 89812800 |
| 7 | 22475653200 |
| 8 | 7791559776000 |
| 9 | 3576325937184000 |
| 10 | 2100278686746240000 |
| 11 | 1536353859354874560000 |
| 12 | 1369954918280131223040000 |
| 13 | 1462916144877711556032000000 |
| 14 | 1843274342545916560600320000000 |
| 15 | 2706157144150223750531344800000000 |
[1,4,90,5040,529200,89812800,22475653200, 7791559776000,3576325937184000, 2100278686746240000,1536353859354874560000, 1369954918280131223040000, 1462916144877711556032000000, 1843274342545916560600320000000, 2706157144150223750531344800000000] |